The g5rv's I've had came with ladder line or 300 ohm twin lead. These had
a pl259 on one and. This line must be isolated from the tower leg with tv
standoffs or such. Mine came with a cable and this cable had a thing
called a current ballon on the end that connects to the ladder line. No
other ballon is needed. I'd just try using a double female. I've
generally had good luck with that antenna.
73s
Butch Bussen
wa0vjr